separating mixtures

DO-NOW Activity

  • Question: Determine which of the following is a physical change:

    1. Sawdust produced by sawing a piece of wood.

    2. Flakes of rust produced on an iron fence.

    3. Heat produced when two room temperature liquids are mixed.

    4. Ashes produced by burning a piece of wood.

Types of Changes in Matter

  • Physical Change: A change that does not alter the chemical identity of a substance.

  • Chemical Change: A change that alters the chemical identity of a substance.

Physical Properties of Substances

  • Physical Properties: Characteristics that can be observed without changing the substance’s chemical identity.

    • Examples include:

      • Length

      • Color

      • Density

      • Mass

      • Pressure

      • Volume

      • Luster

Distinction Between Physical and Chemical Properties

  • Physical Properties:

    • Describe the substance itself.

    • Can be classified as either Extensive or Intensive:

      • Extensive: Depend on the amount of matter present.

        • Examples: Volume, Mass, Energy content (calories).

      • Intensive: Do NOT depend on the amount of matter present.

        • Examples: Boiling Point, Melting Point, Density, Luster.

  • Chemical Properties:

    • Describe a substance's ability to undergo chemical changes.

    • Examples include flammability, radioactivity, corrosiveness, and toxicity.

Density of Matter

  • Definition: How tightly packed matter is, expressing the amount of mass in a given volume.

  • Density Comparison by State of Matter:

    • Gases: Generally less dense.

    • Liquids: Moderate density.

    • Solids: Typically more dense.

Density Formula

  • Formula: Density (P) = Mass (M) / Volume (V)

    • Units: Mass in grams, Volume in liters.

Separating Mixtures

  • Methods of Separation:

    1. Magnetic Removal: Effective when components contain iron, nickel, or cobalt.

    2. Filtration: Separating solids from liquids using a filter; can involve decanting.

    3. Crystallization: Heating a solution allows the solvent to evaporate forming crystals.

    4. Distillation: Separates liquids based on differing boiling points.

    5. Chromatography: Separates mixture components based on their movement across a stationary phase.

Distillation Process

  • Description: A method to separate components based on boiling points.

    • Process Steps:

      1. Heat the mixture to vaporize the component with the lower boiling point.

      2. The vapor moves to a condenser where it cools and reverts to liquid form.

      3. Collect the condensed liquid separately.

Chromatography Principles

  • Description: A technique for separating mixtures based on their movement through stationary and mobile phases.

  • Phases Explained:

    • Stationary Phase: Remains fixed (e.g., paper, gel).

    • Mobile Phase: Solvent that moves (e.g., water, alcohol).

  • Separation Method: Different substances have varying affinities for stationary vs. mobile phases, resulting in different travel speeds.

Solvation: "Like Dissolves Like"

  • Concept: Solubility occurs when substances with similar intermolecular forces interact.

  • Examples:

    • Nonpolar molecules dissolve in nonpolar solvents (e.g., CCl4 in C6H6).

    • Polar molecules dissolve in polar solvents (e.g., C2H5OH in H2O).

    • Ionic compounds are generally soluble in polar solvents (e.g., NaCl in H2O).

Polar vs. Nonpolar Molecules

  • Polar Molecules: Exhibit distinct positive and negative ends, leading to dipole formation.

  • Nonpolar Molecules: Lack distinct poles, often possess multiple charges dispersed uniformly.

  • Solubility Principle: "Like dissolves like" in the interaction of polar and nonpolar substances.